Add a filter to `wp_create_nonce` to allow expired nonces to regenerate if the page is cached

[hailite]

By default, if a page is cached, the related nonce will be cached too. If the page cache's TTL is over 24 hours, the nonce will expire during that time.

By giving the nonce generation function a filter before returning the value, a nonce can have the ability to regenerate for the cache plugins that have ESI or partial/fragment cache functionality.

[spacedmonkey]

@hailite The wp_create_nonce is plugable, as you can replace it all together in your own code. If you need this filter, then you can register your own function. Why does this filter need to be core?

[hailite]

@spacedmonkey Good point. Will override that function. Thanks.

[bordoni]

@spacedmonkey I feel like we should add this filter because even if it's pluggable, it creates problems if multiple plugins overwrite it.

It would for sure allow better control over the creation of nonces.